Triethylamine 2,2,2-Trifluoroethanol

The influence of various buffers on the solvolysis of 5-(trifluoromethanesulfonyloxy)pent-2-yne in anhydrous 2,2,2-trifluoroethanol at 25 C for 24 hours has been studied.24 Sodium and calcium carbonate, 2,6-dimethylpyridine, pyridine and quinoline all favored the formation of four-membered rings, whereas potassium carbonate, triethylamine and sodium 2,2,2-trifluo-roethoxide suppressed formation of the rearranged products. One of the solvolysis products is 2,2,2-trifluoroethyl-2-methylcyclobutenyl ether (see Section 8.A.2.I.). 

The submitters used 99+% 2,2,2-trifluoroethanol, and 99% triethylamine, purchased from Janssen Chimica, without purification. The checkers used the same grade materials purchased from Aldrich Chemical Company, Inc., and Eastman Kodak, respectively. 

The borderline case exo-7-triflyloxybicyclo[4.1.0]heptane (1) is of interest for comparison. Compound 1 solvolyzes at 66 °C in protic solvents HNu (2,2,2-trifluoroethanol, methanol, er -butyl alcohol, acetic acid) containing a small excess of base (triethylamine or sodium acetate) to give exo-7-norcarane derivatives 2 and c -cycloheptenyl derivatives 3 in a virtually constant ratio of 60 40. ... 

Rearrangement of quadricyclyl-7-carbinyl triflate (2). The triflate ester (2), prepared as formulated, on solvolysis in the nonacidic, nonnucleophiUc solvent trifluoroethanol with 1 eq. of triethylamine (scavenger for TfOH) is converted into (3) as the major product. This solvolysis involves a Wagner-Meerwein rearrangement, but does not result in an olefinic product. However, the present... 

Figure 6.16. Solvent-selectivity triangle based on normalized solvatochromic parameters for some common water miscible organic solvents. TEA = triethylamine, THF = tetrahydrofiiran, DMF = N,N-dimethyl-formamide ISP = 2-propanol MeOH = methanol ACN = acetonitrile and TFE = 2,2,2-trifluoroethanol. (From ref. [95] Research Instimte for Medicinal Plants).

Trifluoroethyl methacrylate (MATRIF) and 2,2,2-trifluoroethyl acrylate (ATRIF) monomers are commercially available products, but they can be synthesized from methacryloyl or acryloyle chloride and 2,2,2-trifluoroethanol in the presence of triethylamine as a base [41]. The purification of ATRIF and MATRIF monomers was carried out by distillation (at 59°C/100 mmHg and 46°C/125 mmHg, respectively). 

Solvolysis of the triflate ester of quadricyclyl-7-carbinol (126) in trifluoroethanol containing triethylamine gave (127 80%) and four minor products. Clearly a cyclo-propylethyl carbonium ion rearrangement is involved rather than a direct 1,2-shift to give the quadricyclyl-octyl system (128). ... 

The cycloaddition precursor 227 was prepared by alkylation and decarboxylation of enantiomericaUy pure (3-ketoester 225, which led to ketone 226. Chlorination of 226 was accomplished by quenching the corresponding lithium enolate with triflic chloride to afford a-chloroketone 227. Without purification, a-chloroketone 227 was treated with triethylamine in a solution of 2,2,2-trifluoroethanol and ethyl ether (1 1 mixture). This gave cycloadduct 230 as a 25 1 mixture of isomers in 74% yield from 227 after treatment of 229 with tosic acid. The exquisite stereoselectivity can be rationalized from diene endo attack on the face opposite of the methyl-bearing stereocenter of the cyclic oxyaUylic cation 228. Cycloadduct 230 was then subsequently converted into (+)-dactylol 224 over several steps. 

Trifluoroacetaldehyde, generated from l-ethoxy-2,2,2-trifluoroethanol (4 mmol) by treatment with polyphosphoric acid (PPA), was passed into a toluene solution of (Ry BIN0L-Ti(0-/-Pr)2 (1 mmol) at -78 °C in the presence of 2-propanol (2 mmol) coproduced during the preparation of the catalyst from Ti(0-/-Pr)4 and (i )-binaphthol (BINOL). The resulting hemiacetal was treated with benzoyl chloride, triethylamine and 4-dimethylaminopyridine (DMAP) at -78 °C to afford 2,2,2-trifluoro-l-isopropoxyethyl benzoate (80% ee) in 85% yield. When the esterification was carried out at higher temperatures, % ee of the product considerably decreased due probably to racemization of the intermediate hemiacetal. 

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